plant utilities session1

PLANT UTILITIES

By: A.C.S.I. Mumthas

[BSc. Eng (Hons), AMIE(SL)]

OUTLINE

• Internal Combustion Engines

• Moving Fluid/ Fluid Dynamics

• Hydroelectric generation

• Turbines

INTERNAL COMBUSTION ENGINE– OTTO AND DIESEL CYCLE

INTERNAL COMBUSTION ENGINE– OTTO AND DIESEL CYCLE

• Fuel is burned within the engine, hot combusion

gases make up the working substance to deliver the

useful work

• Thermodynamically open cycle

• In gasoline, diesel engines and gas turbines, the

combustion gases are exhausted from the machine

once they have delivered the work

• Used in automobiles, trucks and air-crafts

• Automobile and truck engines are of two types;

• Gasoline engine- Otto Cycle

• Diesel Engine- Diesel Cycle

OTTO CYCLE

• Ideal air standard cycle

• Uses electrical ignition to

initiate combustion

• Requires 4 strokes

• Used in petrol and gas

engines

• 1-2: Isentropic

compression

• 2-3: Reversible constant

volume heating

• 3-4: Isentropic expansion


volume cooling

combustion

Q=0

Q=0

Work per cycle

= Area inside

DIESEL CYCLE

• Requires no separate

ignition/ no carburetor

• Can be operated at T & P

yielding higher ideal thermal

efficiencies than Otto

• Diesel is cheaper than

gasoline

• Special starting procedure

and excessive weight is

overcome by new

techniques

• More widely adopted by

automobiles

DIESEL CYCLE

• 1-2: Isentropic compression


pressure heating

• 3-4: Isentropic expansion


volume cooling

• Auto ignition results , when

the compression stroke

raises the fuel mixture to a

sufficiently high

temperature

COMPARISON OF OTTO AND DIESEL CYCLES

combustion

Q=0

Q=0

Work per cycle

= Area inside

KALINA CYCLE ENGINE

• 10% more efficient than other heat engines

• Similar to Rankine, but uses two fluids and dual

component vapour enters distillation subsystem

instead discarding them

• Kalina cycle uses mixture of 2 fluids as working fluid,

most commonly used is ammonia and water

mixture.

• Kalina cycle power plants are widely used in

Geothermal stations and waste heat recovery units.

Due to Its unique feature of varying thermo-physical

properties by varying mixture concentration at

different parts of cycle, so They can easily match to

any source (heat addition) and sink (heat rejection)

condition.

KALINA CYCLE ENGINE

• The major difference of Kalina cycle from Rankine

cycle is that in Kalina heat addition and heat

rejection happen at varying temperature even

during phase change, since the fluid is a mixture.

• But in Rankine heat addition and heat rejection

happen at uniform temperature during phase

change.

• This is the one thing which makes all the difference

in performance of Kalina cycle.

• Kalina cycle has got lower average heat rejection

temperature (Tc) and higher average heat addition

temperature (Tb) compared to Rankine cycle. It will

obviously lead to high thermal efficiency.

KALINA CYCLE ENGINE

Comparison of Rankine and Kalina cycles

KALINA CYCLE ENGINE

MOVING FLUID ENERGY

• The study of how fluids behave when they

are in motion is known as fluid dynamics

• Steady Flow

• Fluid passing a given point maintain a steady

velocity

• Can be represented with streamlines showing the

direction of the flow of fluid

• Density of streamline increases as speed increases

• Turbulent flow

• The speed and/or the direction of the flow vary.

MOVING FLUID ENERGY

• Fluids can be compressible or

incompressible.

• Liquids are generally incompressible

• Gases are compressible (i.e. change volume

in response to a change in pressure)

• Fluids can be viscous(pours slowly) or non-

viscous

STREAMLINES: SHOW SPEED

PICTORIALLY. THE CLOSER TOGETHER, THE FASTER THE FLUID IS MOVING.

THE CONTINUITY EQUATION DYNAMIC FLUIDS

WHY WOULD YOU

PUT YOUR THUMB

OVER THE END OF A

GARDEN HOSE?

MASS FLOW RATE

• Since an ideal fluid is incompressible, a fluid

entering one end of a pipe at a certain rate (kg/s)

must leave the other at the same rate. As long as

the pipe has no leaks.

• That rate is called the mass flow rate and is

expressed in kg/s

Avt

Ad

t

V

t

m

Mass Flow

Rate

Constant

From

Density

Formula

CONTINUITY EQUATION

112222 vAvA

Same, incompressable, fluid so roe drops

out!

2211 vAvA

WATER ENTERS THE TUBE BELOW FROM THE LEFT SIDE AT 4

M/S WITH AN OPENING OF RADIUS 5 CM. THE TUBE NARROWS

TO HALF THE RADIUS. WITH WHAT SPEED WILL WATER LEAVE THE RIGHT SIDE?

2211 vAvA

What would happen if the water entered the right side at 4 m/s?

THE BERNOULLI FAMILY : SWISS MATHEMATICIANS IN THE EIGHTEENTH CENTURY

• Daniel Bernoulli (1700–1782), developer of Bernoulli's principle

• Jakob Bernoulli (1654–1705), also known as Jean or Jacques, after whom Bernoulli numbers are named

• Johann Bernoulli (1667–1748)

• Nicolaus I Bernoulli (1687–1759)

• Nicolaus II Bernoulli (1695–1726)

The mathematical ideas developed by the family members include: • Bernoulli differential equation

• Bernoulli distribution

• Bernoulli inequality

• Bernoulli number

• Bernoulli polynomials

• Bernoulli process

• Bernoulli trial • Bernoulli's principle

1. Ideal fluid (incompressible)

2. Non-viscous fluid (laminar flow). No friction.

This is

viscous

FLUID FLOW IS BEST DESCRIBED BY BERNOULLI’S PRINCIPLE

2 assumptions

TWO OBSERVATIONS ABOUT FLOWING FLUIDS IN A PIPE

1. When encountering a region of reduced cross-

sectional area, the pressure always drops! This

obeys ∑F=ma. The fluid in A1 can only speed up

(accelerate) due to an unbalanced force

pushing it. P2 must be way greater than P1.

2ND

2. If a fluid moves to

a higher elevation

the pressure at the

lower level is

greater than that at

the higher level.

We learned that in

the study of static

fluids.

P=ρgh

CONSIDER THESE 2 THINGS HAPPENING AT ONCE

Wouldn’t this create a dramatic drop in pressure?!

BASED ON WORK/ENERGY THEOREM

• Pressure in any fluid is caused by collision forces

which are non-conservative.

1. Non-conservative forces produce work that is

dependant on the path.

2. Net work ≠ 0

. 2

1

. 2

1

. 2

1

. 2

1

.

2

2

2

2

const gh v P

const Vgh Vv PV

const Vgh Vv PAd

const mgh mv d F

const U K W

+ +

+ +

+ +

+ + +

+ +

.2

1 2 constghvP ++

THE BERNOULLI EQUATION

• Shows the

relationship

between:

• Pressure p

• Height h

• Speed v

for an ideal fluid through

any tube of flow

• P1 + ½ v12 + gh1 = P2 + ½ v2 2 + gh 2

.2

1 2 constghvP ++

Prairie dogs do not suffocate in

their burrows. The effect of air

speed on pressures creates

ample circulation. The animal

maintains different shapes to

the 2 entrances of it’s burrows

and because of this the air,

ρ=1.29kg/m3, blows past the

different openings at different

speeds. Assuming the

openings are at the same

vertical level, find the

difference in air pressure

between the openings and

indicate which way the air

circulates.

HYDROELECTRIC POWER (OFTEN CALLED HYDROPOWER) IS CONSIDERED A RENEWABLE ENERGY SOURCE. A RENEWABLE ENERGY SOURCE IS ONE THAT IS NOT DEPLETED (USED UP) IN THE PRODUCTION OF ENERGY. THROUGH HYDROPOWER, THE ENERGY IN FALLING WATER IS CONVERTED INTO ELECTRICITY WITHOUT “USING UP” THE WATER.

HYDROPOWER ENERGY IS ULTIMATELY DERIVED FROM THE SUN, WHICH DRIVES THE WATER CYCLE. IN THE WATER CYCLE, RIVERS ARE RECHARGED IN A CONTINUOUS CYCLE. BECAUSE OF THE FORCE OF GRAVITY, WATER FLOWS FROM HIGH POINTS TO LOW POINTS. THERE IS KINETIC ENERGY EMBODIED IN THE FLOW OF WATER.

WATERWHEEL TECHNOLOGY ADVANCED OVER TIME. TURBINES ARE ADVANCED, VERY EFFICIENT WATERWHEELS. THEY ARE OFTEN ENCLOSED TO FURTHER CAPTURE WATER’S ENERGY.

Not long after the discovery of electricity, it was realized that a

turbine’s mechanical energy could be used to activate a generator

and produce electricity. The first hydroelectric power plant was

constructed in 1882 in Appleton, Wisconsin. It produced 12.5

kilowatts of electricity which was used to light two paper mills and

one home.

HYDROELECTRIC POWER (HYDROPOWER) SYSTEMS CONVERT THE KINETIC ENERGY IN FLOWING WATER INTO ELECTRIC ENERGY.

HOW A HYDROELECTRIC POWER SYSTEM WORKS -

PART 1

F L O WI N G WA T E R I S D I R E C T E D A T A T U R B I N E (R E M E M B E R T U R B I N E S A R E J U S T A D VA N C E D WA T E R W H E E L S ) . T H E F L O WI N G WA T E R C A U S E S T H E T U R B I N E T O R O T A T E , C O N VE R T I N G T H E WA T E R ’ S K I N E T I C E N E R G Y I N T O M E C H A N I C A L E N E R G Y .

THE MECHANICAL ENERGY PRODUCED BY THE TURBINE IS CONVERTED INTO ELECTRIC ENERGY USING A TURBINE GENERATOR. INSIDE THE GENERATOR, THE SHAFT OF THE TURBINE SPINS A MAGNET INSIDE COILS OF COPPER WIRE. IT IS A FACT OF NATURE THAT MOVING A MAGNET NEAR A CONDUCTOR CAUSES AN ELECTRIC CURRENT.

How a Hydroelectric Power System Works – Part 2

The amount of electricity that can be generated by a hydropower

plant depends on two factors:

• flow rate - the quantity of water flowing in a given time; and

• head - the height from which the water falls.

The greater the flow and head, the more electricity produced.

How much electricity can be generated

by a hydroelectric power plant?

When more water flows through a turbine, more electricity can be

produced. The flow rate depends on the size of the river and the

amount of water flowing in it. Power production is considered to be

directly proportional to river flow. That is, twice as much water

flowing will produce twice as much electricity.

Flow Rate = the quantity of water flowing

The farther the water falls, the more power it has. The higher the

dam, the farther the water falls, producing more hydroelectric power.

Power production is also directly proportional to head. That is,

water falling twice as far will produce twice as much electricity.

Head = the height from which water falls

It is important to note that

when determining head,

hydrologists take into

account the pressure behind

the water. Water behind the

dam puts pressure on the

falling water.

Power = the electric power in kilowatts or kW

Head = the distance the water falls (measured in feet)

Flow = the amount of water flowing (measured in cubic feet per second

or cfs)

Efficiency = How well the turbine and generator convert the power of

falling water into electric power. This can range from 60%

(0.60) for older, poorly maintained hydroplants to 90%

(0.90) for newer, well maintained plants.

11.8 = Index that converts units of feet and seconds into kilowatts

A standard equation for calculating energy

production:

Power = (Head) x (Flow) x (Efficiency)

11.8

As an example, let’s see how much power can be generated by the

power plant at Roosevelt Dam, the uppermost dam on the Salt River

in Arizona.

Although the dam itself is 357 feet high, the head (distance the

water falls) is 235 feet. The typical flow rate is 2200 cfs. Let’s say

the turbine and generator are 80% efficient.

Power = (Head) x (Flow) x (Efficiency)

11.8

Power = 235ft. x 2200 cfs x .80

11.8

Power = 517,000 x .80

11.8

Power = 413,600

11.8

Power = 35,051 kilowatts (kW)

Roosevelt’s generator is actually rated at a capacity of

36,000 kW.

Tall dams are sometimes

referred to as “high-head”

hydropower systems. That

is, the height from which

water falls is relatively high.

High-head Hydropower

Many smaller

hydropower systems

are considered “low-

head” because the

height from which the

water falls is fairly low.

Low-head hydropower

systems are generally

less than 20 feet high.

Low-head Hydropower

Environmental Considerations

High-head hydropower systems can produce a tremendous amount

of power. However, large hydropower facilities, while essentially

pollution-free to operate, still have undesirable effects on the

environment.

Installation of new large hydropower projects today is very

controversial because of their negative environmental impacts.

These include:

upstream flooding

declining fish populations

decreased water quality and flow

reduced quality of upstream and downstream environments

Glen Canyon June 1962 Glen Canyon June 1964

Scientists today are seeking ways to develop hydropower plants that

have less impact on the environment. One way is through low-head

hydropower. Low-head hydropower projects are usually low impact

as well—that is, they have fewer negative effects on the environment.

Example of a low-head, low impact hydropower system.

Low-head and Low Impact Hydropower

• river flow

• water quality

• watershed

protection

• fish passage

and protection

A hydropower project is considered low impact if it considers

these environmental factors:

• threatened and

endangered species

protection

• cultural resource

protection

• recreation

• facilities recommended

for removal

Low Impact Hydropower

The two primary types of hydropower facilities are the

impoundment system (or dam) and the run-of-the-river

system.

Types of Hydropower Facilities

An impoundment is simply a dam that holds water in a reservoir.

The water is released when needed through a penstock, to drive the

turbine.

This illustration shows the parts of a standard hydroelectric dam.

Most large, high-head hydropower facilities use impoundments.

Impoundment System

Run-of-the-River Hydropower System

A run-of-the-river system uses the river’s natural flow and

requires little or no impoundment. It may involve a diversion of a

portion of the stream through a canal or penstock, or it may involve

placement of a turbine right in the stream channel. Run-of-the-river

systems are often low-head.

Hydropower Plants Also Vary in Size

There are large power plants that produce hundreds of megawatts of

electricity and serve thousands of families.

There are also small and micro hydropower plants that individuals

can operate for their own energy needs. The Department of Energy

classifies power plants by how much energy they are able to

produce.

A large hydropower

facility has the capacity

to produce more than

30,000 kilowatts (kW) of

electricity.

Large hydropower

systems typically require

a dam.

Large Hydropower

Small Hydropower

Small hydropower facilities

can produce

100 – 30,000 kilowatts (kW)

of electricity.

Small hydropower facilities

may involve a small dam, or

be a diversion of the main

stream, or be a

run-of-the-river system.

Micro hydropower

plants have the

capacity to produce

100 kilowatts (kW)

or less.

Micro-hydro facilities

typically use a

run-of-the-river

system.

Micro Hydropower

Hydropower is an important renewable

energy source world wide...

DEFINITION

A Turbine is a Form of Engine Requires a suitable

working fluid in order to function- a source of High

Grade Energy and a Sink for Low Grade energy.

When a Fluid Flows through the Turbine ,Part of

Energy Content is Continuously Extracted and

Converted in to Useful mechanical Work.

1.INTRODUCTION:- The device in which the kinetic ,potential or

intermolecular energy held by the fluid is

converted in the form of mechanical energy

of a rotating member is known as a turbine .

Also , defined as all machines in which hydraulic energy

is transferred into mechanical energy (in the form of

rotating shaft ) ,or in some other moving parts are

known as ‘turbines’ or hydraulic motors.

TURBINE:-

.A simple design of a turbine contain as rotor assembly,

which is the moving part, having shaft or drums with

blades attached to them. The movement of the blades,

which is caused by the flow of fluids, creates rotational

energy which is imparted to the rotor. Some example of

turbine impulse , Reaction etc.

The first „turbine” was made by Hero of Alexandria in the second century.

In the end of XVIII century the

Industrial Revolution began (in 1770 first reciprocating piston steam engine invented by Thomas Newcomen and invented by James Watt started its work).

The first steam turbines were

constructed in 1883 by Dr Gustaf de Laval and in 1884 by sir Charles Parsons.

In1896 Charles Curtis received a patent on impulse turbine

In 1910 was created radial turbine .

Some historical facts

http://www.history.rochester.edu/steam/parsons/Fig_4.GIF

PRICIPLE OF STEAM TURBINE

Steam turbine depends completely upon the dynamic

action of the steam. According to Newton’s second law of motion, the FORCE is

proportional to the rate of change of MOMENTUM (mass x velocity). If the rate of

change of momentum is caused in the steam by allowing a high velocity jet of steam

to pass over curved blade, the steam will impart a force to the blade. If the blade is

free, it will free off (rotate) in the direction of force.

The steam from the boiler is expanded in a passage or nozzle ,

where due to fall in pressure of steam is converted into Kinetic energy of steam & this

KE of steam is converted into work moving blade

Moving Blade

Force = mc1 - mc2

mc1

mc2

TYPES OF TURBINE On the basis of principle of operation

Impulse turbine

Reaction turbine

Impulse- Reaction turbine

Impulse Turbine

In impulse the drop in pressure of steam takes place only in

nozzle & not in moving blades. This is obtained by making the

blade passage of constant cross section area it may be

noted that energy transformation takes place only in nozzles.

Moving blades only cause energy transfer.

X

X

X

A flowing or working fluid contains kinetic as well as potential

energy and the fluid may be compressible as well as

incompressible. The energy of these fluids is trapped by turbines

in several ways.

Impulse turbines-

The impulse generated by changing the direction of flow of high

velocity fluid or gas jet is used to spin the turbine.

This leaves the fluid flow with a decreased amount of kinetic

energy.

The fluid or gases in the turbine blades have no pressure change

and the entire pressure drop takes place in the stationery

blades.

The fluid is accelerated using a nozzle, which changes its

pressure head to velocity head. This is done before the fluid

reaches to turbine. The transfer of energy in impulse turbines is

described by Newton’s second law of motion.

THEORIES OF OPERATIONS OF TURBINES

IMPULSE TURBINE BLADE

REACTION TURBINE BLADE

A torque is developed in these turbines when they

react to the gas or the fluid pressure or the mass.

When the gas or fluid passes through the turbine rotor

blades, the pressures in the system changes. The

turbine must be fully immersed in the flowing fluid and

the pressure casement is also provided for a working

fluid.

The primary function of the working fluid is to contain

and direct the working fluid. It also maintains the

functions imparted by the draft tubes in water turbines.

This concept is used in most steam turbines including

the Francis turbine. Newton’s third law is used to

describe the transfer of energy in reaction turbines.

REACTION TURBINES

Reaction turbine:- Pressure drop take place in rotor

(M.B.). Energy transformation takes place in rotor. Energy transfer only in rotor.

Impulse- Reaction turbine:- In this turbine drop in

pressure of steam takes place in fixed blade as well as moving blade. It may be noted that energy transformation occur in both fixed blade & moving blade. The rotor blade cause energy transfer & energy transformation.

COMPOUNDING

Compounding of Impulse turbine :-

One row of nozzles followed by one row of blades is called a stage of turbines. Compounding is a method for reducing the rotational speed of the impulse turbine to practical limit. Boiler pressure down to condenser pressure in a single stages so high RPM & large diameter of turbine.

Three type of compounding

Pressure compounding

Velocity compounding

Pr & velocity compounding

CROSS SECTIONAL VIEW OF TURBINE

plant utilities session1

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